1. Technical Field
The present invention pertains to improvements in methods and apparatus for encapsulating particulate material, in particular, microparticulates and granules, in the manufacture of pharmaceutical products for oral dosage or delivery.
2. Discussion of the Related Art
Various pharmaceutical products are packaged in the form of capsules for oral dosage and controlled release of a pharmaceutically active composition within an individual""s body. Oral dosage pharmaceutical capsules are typically filled with microparticulate material or granules on the order of several microns in dimension (e.g., greater than about 100 xcexcm). The encapsulated particles typically contain a select amount of one or more pharmaceutically active compositions along with one or more inert excipient materials. In a typical encapsulation process, a source of particulate material or particles to be encapsulated is transferred by gravity from a hopper to a dosator, where the dosator determines the amount of particles to be added to each capsule. The dosator transfers the requisite amount of particles into an open capsule (e.g., an open shell portion of the capsule), and the open capsule is then sealed (e.g., by placing a shell cap over the open shell portion filled with particles).
Depending upon the physical attributes of the particles to be encapsulated for the oral dosage product (e.g., variations in particle size, tackiness of the particulate material, irregularities in particle surface geometries, etc.), problems may occur in the transfer of the particles from the hopper to the dosator. When utilizing a pharmaceutical material that is difficult to encapsulate, voids can be created in the hopper at locations previously occupied by particles transferred into the dosator, where the particulate material remaining within the hopper may not readily fill such voids. This can be a significant problem, for example, when the particles to be encapsulated have non-spherical and irregular geometric surfaces, which causes the particles to frictionally adhere to each other, rather than sliding with respect to each other, as the particles are gravity fed from the hopper to the dosator. The generation of voids within the hopper in turn leads to significant and undesirable deviations in the amount of particles transferred to the dosator and, thus, to the pharmaceutical capsules being produced. In preparing product capsules with particulate material that is difficult to encapsulate, the capsules tend to decrease in fill weight during the production process, with unfilled voids increasing in size until very little or no particles are transferred from the hopper to the dosator.
Attempts at overcoming the aforementioned problems utilizing conventional methods result in further particulate flow problems within the hopper and/or degradation of desirable properties of the particles. For example, if the hopper is vibrated in an attempt to eliminate voids within the particle bed, the particles can become compacted, particularly when the hopper circumference is reduced (e.g., funnel shaped) near the outlet, resulting in reduced or no flow of particles from the hopper into the dosator. Mechanical stirring within the particle bed to inhibit the formation of voids can lead to crushing of particles, which reduces particle size from a desired range and results in undesirable deviations in the dissolution profiles for resultant oral dosage capsule products.
Thus, an improved system and method is desirable for ensuring accurate dosage amounts of particulate material in the production of oral dosage pharmaceutical products, particularly capsule products having particle dimensions greater than about 100 xcexcm and irregular and non-spherical shaped geometries.
Therefore, in light of the above, and for other reasons that become apparent when the invention is fully described, an object of the present invention is to manufacture oral dosage pharmaceutical products, such as capsule products, including particles with irregular and non-spherical shaped geometries.
It is another object of the present invention to manufacture oral dosage pharmaceutical products including particles with dimensions greater than about 100 xcexcm.
It is yet another object of the present invention to manufacture oral dosage pharmaceutical products including particles with irregular geometries where the products do not deviate significantly from a desired or target fill weight.
It is a further object of the present invention to manufacture oral dosage pharmaceutical products including a substantially uniform blend of particles with varying irregular shapes and sizes.
The aforesaid objects are achieved individually and/or in combination, and it is not intended that the present invention be construed as requiring two or more of the objects to be combined unless expressly required by the claims attached hereto.
According to the present invention, oral dosage pharmaceutical products are produced including particles with irregular geometries utilizing a system including a hopper and a dosator. The hopper receives particulate material that includes particles having irregular geometries as defined by a roundness value of no greater than about 0.40. A gaseous fluid is directed into the hopper to fluidize at least some of the particles within the hopper. A selected amount of the particulate material is transferred from the hopper into the dosator, and an oral dosage pharmaceutical product is formed from the selected amount of particulate material expelled from the dosator. The formation of voids within the particles disposed within the hopper is prevented or minimized by fluidizing particles within the hopper prior to delivery to the dosator. Oral dosage pharmaceutical capsules are formed in accordance with the present invention that contain particles of irregular geometries and sizes greater than about 100 xcexcm while substantially maintaining the capsule weight and particle size distribution of each capsule within a desired range. Preferably, a majority of the capsules in a production batch do not deviate from a target fill weight by more than about 15%, and the average fill weight of a single capsule in the batch does not deviate from the target fill weight by more than about 10%.
The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description.